As stored program controlled switching systems have evolved, a wide variety of useful features have been developed to extend the communication capabilities such systems provide. One class of features relates to redirecting calls. Consider an example where a customer calls a business and the call is answered by a general customer representative. The representative and the customer talk for a few minutes and the representative determines that the customer should talk to a specialist. The representative then transfers the call to the specialist. If the representative wants to talk with either the specialist or the customer at the end of the call, the representative needs to stay on the line as the customer talks to the specialist. This is wasteful of network resources, e.g., a conference bridge, but even more significantly, it wastes the representative's time.
Further, known transferring switching systems have billing service problems. Referring to FIG. 33, an example of a known centrex or ISDN system is shown. Call transfer in this centrex or ISDN environment allows subscribers to receive or originate a call, receive or originate a second call concurrent with the first call, join the two calls together into a 3-way call, and disconnect from the call while allowing the other two parties to continue talking. A state diagram and call flow of these actions are shown in FIGS. 34 and 35.
The following scenario will consider call-transfer from the perspective of a 2ndStation that receives a call from a 1stStation, and transfers that call to a 3rdStation, yielding a conversation between the 1stStation and the 3rdStation (the 2ndStation has disconnected). In standard telecommunications terminology the 1stStation is frequently called the calling party, the 2ndStation is typically referred to as the transferring party, and the 3rdStation is often called the transferred-to party.
In current practice, a transferred call is routed from the switching office of the 1stStation (termed the 1stSwitch) to the 2ndSwitch to the 3rdSwitch, even after the 2ndStation has disconnected.
In current practice, the originating switch of the first call produces a bill that is handled independently from the bill generated by the originating switch of the second call (even if the same switch is involved for both call originations).
Each originated call generates a billing record: the call from the 1stStation to the 2ndStation; the call from the 2ndStation to the 3rdStation. Both calls terminate when the 1stStation or 3rdStation disconnect. The billing practice does not reflect the time at which the 2ndStation disconnects.
If the 3rdStation were to initiate a 3rd call (a second transfer) while talking with the 1stStation, then a third bill would be created for the call from the 3rdStation to the 4thStation (the 4thStation may be equivalent to the 2ndStation if the 3rdStation transfers the call back to the 2ndStation). In this case, all three bills would depend upon the disconnect time of the 1st or 4thStation (and would not reflect the disconnect times of the 2nd or 3rdStations). Event diagrams for Scenario A are shown in FIGS. 36 and 37. An event diagram for Scenario B is shown in FIG. 38. Refer to Table 3 for Scenario A and Table 4 for Scenario B.
TABLE 3 ______________________________________ Segment 1: oiginating time = A.sub.o terminating time = C.sub.o Segment 2: originating time = C.sub.o terminating time = C.sub.t Billing Practice: current practice, Bill 1: A.sub.t - A.sub.o (originator of call: 1stStation) bill based on tariff for 1stStation to 2ndStation calls; bill generated by 1stSwitching office; bill produced when 1stStation or 3rdStation disconnect current practice, Bill 2: C.sub.t - C.sub.o (originator of call: 2ndStation) bill based on tariff for 2ndStation to 3rdStation calls; bill generated by 2ndSwitching office; bill produced when 1stStation or 3rdStation disconnect current practice, Bill 2: A.sub.t - C.sub.o (originator of call: 2ndStation) current practice, Bill 3: A.sub.t - B'.sub.o (originator of call: 3rdStation) No bill created based on 1stStation to 3rdStation distance. Bill for second call not dependent upon 2ndStation disconnect. ______________________________________
TABLE 4 ______________________________________ Segment 1: originating time = A.sub.o terminating time = C.sub.o Segment 2: originating time = C.sub.o terminating time = B'.sub.o Segment 3: originating time = B'.sub.o terminating time = B'.sub.t or A.sub.t Overlap between Segments 1 and 2 = B.sub.d - C.sub.o Overlap between Segments 2 and 3 = C.sub.d - B.sub.o Caller Total Duration: A.sub.t - A.sub.o 2ndStation actual duration: (B.sub.d - B.sub.o) + ($B'.sub.t - B'.sub.o) 3rdStation actual duration: (C.sub.d - C.sub.o) current practice, Bill 1: A.sub.o - A.sub.o (originator of call: 1stStation) ______________________________________
The billings shown in Tables 3 and 4 represents the amount of switching system resources used by the call scenarios: they do not however represent the benefit that the parties to the call derived from the call. Thus, there is a need for a billing method that more closely bills for the benefit of a call to the callers for what is closer to a two party call than a three party conference call.
Recent years have seen an increase in the use of switch adjuncts for providing telecommunication services. Examples of such adjuncts include PBXs, voice mail systems, and service circuit nodes. In many services, the adjunct performs a role similar to that of the customer representative in the above example in that the adjunct transfers the call to a third party. If the service requires the adjunct to resume call control after the customer-specialist conversation is over, the adjunct must stay involved with the call throughout the customer-specialist conversation. In cases where a switch included in the adjunct provides part of the initial connection from a caller to a called party, a subsequent transfer of the call to a third party requires a continued connection through the adjunct switch even though the initial called party may not be associated with the adjunct. In all such services, both network and adjunct resources are wasted. A further problem is that adjuncts that provide telecommunication services over open interfaces, e.g., an ISDN basic rate interface (BRI), often do not have the high reliability or traffic beating capacity of central switching equipment. These deficiencies are more significant when a talking path is established through the adjunct and such path must be maintained after a call is transferred.
Solution
These problems are solved and a technical advance is achieved in accordance with the principles of the invention in a call processing method where a transferring station can be disconnected from a call after the call is transferred to a third station, but where the call is automatically returned to the transferring station in response to either disconnect signaling or other predefined signaling, e.g., a flash or a dual-tone-multi-frequency (DTMF) tone, advantageously without requiring any station to dial the transferring station. The transferring station is for a subscriber to a new transfer feature referred to as a transfer-with-return. The feature is invoked for the call either in response to a signal from the transferring station requesting invocation of the feature or because the subscriber has only the transfer-with-return feature and no other transfer feature. The call is also returned in response to a busy or no answer condition of the third station. In an arrangement comprising a switching system connected to the transferring station, and an adjunct switch also connected to the switching system, the initial connection may be from the calling station through the switching system, the adjunct switch, and back through the switching system to the transferring station. After the transfer, the connection need not go through the adjunct switch.
A call processing method in accordance with the invention includes connecting a call from a first station to a second station. The call is then transferred from one of the first and second stations to a third station, for communication between the other of the first and second stations and the third station. The one station is for a subscriber to a transfer-with-return feature. The feature is invoked for the call. At some point, the one station is disconnected from the call. The call is automatically returned to the one station in response to a prespecified event and without receiving a dialed number for the one station.
The invention is used in three illustrative services described herein and referred to as Services 1, 2, and 3. In Service 1 (FIGS. 1 and 2), the transferring station is for a human attendant. In Service 2 (FIGS. 13 and 14), the transferring station is a service circuit node (SCN). In Service 3 (FIGS. 15 and 16), the transferring station is an external service module (ESM).
The prespecified event resulting in the automatic return could be receiving disconnect signaling from only one of the other and third stations. The prespecified event could also be receiving predefined signaling, e.g., a flash or DTMF tone, from one of the other and third station. Finally, the prespecified event could be detecting a busy or no answer condition of the third station.
In response to disconnect signaling from both the other and third stations, the one station is notified of the end of the call.
The call transfer is effected in one of three ways: blind transfer, consultation, or conference. With blind transfer, the other station and the third station are connected without having previously connected the one station and the third station for a two-way consultation. With consultation, the one station and the third station are connected for two-way consultation and thereafter the other station and the third station are connected. With conference, the one station, the other station, and the third station are initially connected for a conference and the one station subsequently drops out.
The one station is provided with call history information, e.g., call identification information defining the call as a return call, and defining the reason for the return, for use at the one station in answering or subsequently controlling the return call.
The one station may be connected back in with the other and third stations for conference as part of the automatic return. Alternatively, the one station may be connected with the other station and the third station may be connected with the other station.
If the one station is part of a group of stations, e.g, a multi-line hunt group or automatic call distributor group, that are accessible via one or more common directory numbers, the call is returned to the one station rather than any other station of the group.
In an arrangement comprising a host switching system and an adjunct switch connected to the host system, the illustrative method may be performed by either the host system or the adjunct switch.
A further call processing method in accordance with the invention includes connecting a call from a first station to a second station. The call is then transferred from one of the first and second stations to a third station, for communication between the other of the first and second stations and the third station. At some point, the one station is disconnected from the call. In response to disconnect signaling from both the other and the third stations, the previously disconnected one station is notified of the end of the call.